One of the most important ingredients in a successful garden is also one of the most neglected: the soil. Rich, healthy soil gives plants what they need to thrive, but first you must give the soil what it needs.
Composed of various tiny rock particles or minerals, organic matter, water and air, soil is also home to many living things, such as plants, bacteria, insects and microorganisms. The amount and type of each of these components determine the texture and structure of the soil, and two handfuls can vary greatly.
You would expect the soil in coastal Florida to be different from that in Connecticut, but did you know that it also can vary within your yard? For example, near a house’s foundation, soil often will be alkaline from lime leaching out of the cement.
All soil contains sand, silt and clay, the three kinds of particles that make up about 50 percent of soil. In the ideal soil, called loam, they are found in roughly equal proportions.
When there’s too much sand, the soil doesn’t hold water well (the inorganic particles can’t absorb moisture); too much clay can mean a shortage of air (because there’s not enough space between the particles). You can correct these problems and others with soil amendments–but first you must determine the composition of soil in your garden.
Start by performing a hands-on test a few days after a rain: Rub a small amount of soil between your thumb and forefinger.
Does it feel gritty? Then the soil is sandy, which is common in coastal regions. Or does it feel like moist flour or talcum powder? This indicates silt, which often is found in the Midwest. Is it slippery and moldable, or sticky? This tells you there’s a lot of clay in the soil, which often is the case in the South.
This gives you only a general idea of your soil, and there is much more to learn. If yours is a new garden or you’ve never had samples analyzed, do so now. Home test kits are available, but most are not as accurate or extensive as those done by private soil-testing labs, which can be found in the Yellow Pages. Test results will reveal your soil’s organic content, pH and information about the necessary nutrients the soil contains (or lacks); the lab also will provide recommendations for correcting problems.
Questions about soil testing are answered by the University of Illinois Cooperative Extension Service at 773-292-4444 between 9 a.m. and noon Mondays, Wednesdays and Fridays. Ask for the Master Gardener program. The service also provides a brochure about soil testing.
There are two ways to amend soil: chemically and physically. Chemical soil amenders include lime, which alters pH, and packaged fertilizers containing nitrogen, phosphorus and potassium. These are easy to use, but there is no substitute for physically enriching the earth with organic materials such as compost and inorganic materials such as sand.
Adding organic material is, without a doubt, the most important thing you can do for your soil, and compost is the best all-around amendment. It helps make air and water available to plants and eases root penetration. Some composts even make the soil more fertile. Incorporating compost is also a great way to correct a soil with too much clay or sand.
To add compost, turn the soil once, then dig or till the compost in. Six inches of compost in the first foot of soil is good, and a foot of compost in the first 1 1/2 feet of soil is even better.
Certain plants also will boost your soil’s organic content. Known as green manures, these grasses or legumes–winter rye, hairy vetch and various clovers are common ones–are grown from seed, then turned under while the plants are young. As they break down, they add bulk and nitrogen to the soil.
Planting the right crop at the right time is crucial (many are sown in the fall and tilled in the spring); consult your cooperative extension or a good seed catalog for advice for your area.
A few more effective soil amendments include greensand, which is high in potassium and opens up the soil; bone meal, for phosphorus and calcium; rock dusts, for phosphorus; and cottonseed meal and dried blood, for nitrogen.
Sand lightens clay soil, but large amounts are necessary to make a difference. Lime and sulfur correct soil’s pH, and should be used only according to your pH test recommendations and package instructions. Organic mulches protect soil, shade roots, slow evaporation and eventually break down and benefit the soil.
Two more important rules: Don’t overtill the soil, and never walk on or work on wet soil. Both of these disrupt the delicate balance of life underground.
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Martha Stewart welcomes letters. She cannot reply individually, but you may write to her in care of the Chicago Tribune, Home section, 435 N. Michigan Ave., Chicago, Ill. 60611. Or send e-mail to TribHome@aol.com.
